Патент USA US2120995код для вставки
June 21, 1938. A. VAN- DE RlET 2,120,995 AMPLIFYING ARRANGEMENT Filed Jan. 25,_ 1933 .1 INVENTOR ' ABFaAHAM VAN DE RIET ATTORNEY 2,120,995 Patented June 21, 1938 VUNITE’D ‘STATES PATENT oFFics " ' 7' V _ ’ 2,120,995 _ ' Abraham van de Biet, Eindhoven, Netherlands, ,assignor to Radio Corporation of America a corporation of Delaware . "Application . I In the January Netherlands 23, 1983,-‘Serial April 26, 1932 No.~a652,996‘ ' . 5 Claims. (Cl. 179L171“).- . feeble signals, also, the direct current energy the alternating current energy delivered by an delivered is smaller than in the case of power amplifying valve without the mean anode dis sipationv being exceeded. At a given anode dissipation the alternating current energy delivered by an amplifying valve can only be increased if at the same time the 7 direct current energy delivered'is reduced. A re-' ii) duction of the direct current energy in the output circuit can be obtained at a given anode voltage by the use of a negative grid bias. The value of this grid bias is, however, limited by the condi tion that the valve should always operate on a 15 This arrangement ensures that in the case of This invention has reference to amplifying ar rangements, and provides means for increasing linear part of the‘ anode current-grid voltage ful signals. Thus, the total direct current energy delivered decreases when receiving weak signals, UK whereas, the alternating current energy delivered remains unvaried so that the total quantity of energy delivered is reduced, and the tube is not fully loaded. . Consequently, the primarily im pressed signal voltage can be increased. This results in an increase of anode direct and alter nating current energy until the admissible load of the tube is reached again. The circuit arrangement according to the in vention is particularly’ advantageous for valves 15 characteristic curve. That is to say, the algebraic having to deliver a high power; consequently, for sum of the negative grid bias and the maximum ‘ example, for the last valve,v in an amplifying cir alternating voltage to be ampli?ed should not be cuit arrangement. The alternating current so large that the valve operates on a curved part energy deliverediby a given type of amplifying valve is increased by the use of the invention. 20 of the characteristic. ‘ ‘In order that the invention may be clearly In well known circuit arrangements, generally, constantvoltages are supplied to the anode and understood and readily carried into effect two grid of the amplifying valve. The value of these embodiments thereof will now be described more voltages is dependent upon the conditions that fully with reference to the accompanying draw ing, in which: ' 25 a given anode dissipation should not be ex ,Fig. 1 shows thelast amplifying stage of a bat ceeded, and that a certain maximum voltage shouldbe ‘susceptible to. a. linear ampli?cation. tery receiver embodying the invention; ‘Independently of the value of the alternating Fig. 2 shows a modi?cation employing power voltage vto be ampli?ed at a given moment, a, amplifier supplied with alternating current. constantdirect current energy'is delivered by a Referring to Fig. 1, I designates ‘a thermionic‘ valve adjusted in the manner .of said well'known valve illustrated as a screen grid valve. vIts input circuit includes an impedance 2 which is, forex ample, the secondary of a transformer to which which the direct current energy delivered is not , thevoltages to be ampli?ed are supplied. The constant, and in which this energy is, smaller output circuit of the valve includes anoutput im than in the. case above described so that a higher pedance 9; for example, the primary of a transa alternating current energy can be admitted for a former to which a loudspeaker may be connected. given valve. The amplifying arrangement, ac The screen grid is connected to a point of the, cording to the invention,’ is characterized by a anode voltage battery (not shown to preserve 40 grid bias which is so variable with the signal _ _ , voltage to be ampli?ed that when the signal simplicity of disclosure). arrangements. , l .. . . The invention provides for an arrangement in 40 voltage decreases the grid bias becomes more negative. ‘ Thus, in thecase of ‘feeble signals; a high, and, in the, case of more powerful signals, a lower negative grid bias is applied to the ampli?er valve. In any case this grid biasv should besuch that the algebraic sum of the bias and of the voltage to be ampli?ed is smaller than a voltage by which the , valve would be adjusted to a curved partof the characteristic curve.’ Preferably, the adjustment is such that the. sum hereinbefore indicatedof. the grid voltages is substantially constant, and is so large as to prevent :thevalve 'fromiop'erating 55 , onacurved part of the characteristic, The valves used may comprise directly, or in directly,‘ heated cathodes which are supplied with direct, or alternating, current. Generally, it is desirable to withdraw the voltages to be recti?ed 45 fromthe output circuit of the ampli?er, as the . voltages which occur in the input [circuit are often too small to ensure a proper control, and moreover, a connection of the recti?er in parallel with the input. circuit results in a rather great 50 decrease of the ampli?cation. Generally, there fore, a part of the output voltage will be recti ?ed, and in this .caseisaid part should be so large that-the grid voltage of the amplifying valveiis constantly as much as ‘possible negative but 55 2,120,995 always so that no operation ensues in a curved the negative bias of grid I is reduced by the part. positive voltage across resistor 4|. Each of re sistors 4|] and 4| is shunted by a condenser of . The diagram shown in Fig. 1 represents the last stage of a battery ampli?er and can be used, for example, in a portable set. Such a device is always supplied with direct current. In this case it is important that the cathodes of all the valves should be connected to the same source of voltage. This condition is satis?ed in the circuit arrange 10 ment illustrated. A triode I2 which is connected low impedance to signal currents. Resistor Ell functions as a high impedance to signal cur rents; condenser 5| is a path of low impedance to current from source 3I. While I have indicated anddescribed several systems for carrying my invention into effect, it will be apparent to one skilled in the art that as a grid detector is used as the recti?er. The my invention is by no means limited to the anode circuit of this valve includes a high resist particular organizations shown and described, ance I3. When no signal is impressed on the in but that many modi?cations may be made with put circuit 2 of valve I, the anode current of valve 7 out departing from. the scope of my invention as I2 is a maximum. ‘set forth in the appended claims. 15 The potential drop across the resistance I3 is ‘ " What is claimed is: thus high, and the voltage at the plate of valve I2 is consequently low. This voltage .summed up with the voltage of battery I‘! is supplied to the , 20 grid of valve I by means of a potentiometer M, I5, H3; Thus, the negative grid voltage of this valve is rendered a maximum, but the grid voltage is not negative enough to operate the tube on the curved portion of the characteristic. Now, if an 25 alternating voltage is supplied to the input cir cuit of valve I, this results in that the voltage at the input circuit of the detector is lowered, the current passing through resistance I3 decreases, and the voltage at the plate of valve I2 conse 30 quently increases. Thus, the grid voltage of valve I becomes less negative. The grid bias is smoothed by means of condensers I8 and Ill. The condensers 20 and 2| constitute a capacita tive potentiometer on the output circuit by which 35 a desired part of the voltage is supplied to the detector valve. The condenser 20 serves simul taneously as a grid condenser. for this detector valve. ' If a ?nal valve of very great power is used,‘ 40. preferably an arrangement as shown in Fig. 2 may be utilized. In this arrangement use is made of valves supplied with alternating cur rent. The grid bias for the amplifying valve is delivered by two recti?ers preferably housed in one valve and having one common cathode. The recti?er formed by the cathode 23 and the anode 24 is connected to a winding 39 of the public supply transformer 3| and consequently delivers a constant recti?ed voltage. The recti 50 ?er formed by the cathode 23 and the anode 25 is connected to a part of the output impedance 9 of valve‘I so that this recti?er produces volt ages the'value of which depends on the signal voltage. The two recti?ed voltages are smoothed in known manner, and are supplied in opposite directions to the input circuit of the amplifying ,1.,In combination ‘with an audio frequency ampli?er, an audio frequency signal input cir cuit coupled to the ampli?er input electrodes, an output circuit coupled to the output electrodes 20 of the ampli?er, a source of alternating current potential, a diode recti?er coupled to said. source, 'a direct current connection between said input circuit and the diode anode whereby the ampli ?er signal grid is maintained at a negative di 25 rect current potential with respect to the cath ode, and means, responsive to variations in the ampli?er output amplitude, for varying said sig nal grid bias. 2. In combination with an audio frequency 30 ampli?er, an audio frequency signal input cir cuit coupled to the ampli?er input electrodes, an output circuit coupled to the output electrodes of the ampli?er, a source of alternating current potential, a diode recti?er coupled to said source, 35 and a direct current connection between said input circuit and the diode anode whereby the ampli?er signal grid is maintained at a negative direct current potential with respect to the oath ode, a second anode in the envelope of said di 40 ode, and a path of ‘low impedance to the audio output of said ampli?er connected between the ampli?er output circuit and said second anode. 3. In combination with an audio frequency ampli?er, an audio frequency signal input cir cuit coupled to the ampli?er input electrodes, an output circuit coupled to the output elec trodes of the ampli?er, a source of alternating current potential, a diode recti?er coupled to said source, and a direct current connection be 50 tween ‘said' input circuit and the diode anode whereby the ampli?er signal grid is maintained at a negative direct current‘ potential with re spect ‘to the cathode, said diode being provided with a second anode adjacent the diode cath 55 ode, a signal connection between the ampli?er valve so that the bias of this valve varies in output circuit and the second anode, said diode , the desired manner with the signalintensity. The current from supply source 3| is recti?ed, cathode and second anode being connected to gether to‘providea diode recti?er for develop 60 and develops across resistor 40 a direct current ing a biasing direct current voltage from am voltage. Since the signal grid is connected to the anode side of resistor 40, the signal grid is pli?ed signal currents which biases said ampli ?er in a direction to increase the ampli?er plate negatively biased to a constant value; as ex current flow. 4. In, combination with a source of audio fre quency signals, an audio frequency signal am plained previously this‘ value is not great enough 65 to operate the tube I on the curved portion of the characteristic- A portion of the signal en ergy is recti?ed by diode 25—23; resistor 1H hav ing developed thereacross a direct current volt age proportional in magnitude to'the signal in tensity. Since the resistor 4| is connected in series between the cathode of tube I and re sistor 40, and the positive end of the latter is connected to- the positive terminal of resistor 4|, the voltages across bothresistors oppose each 751 other. ,I-Ience, with increasing signal intensity pli?er, a potential source for applying a c0n~ stant negative bias to the ‘amplifier grid suffi cient in magnitude to adjust theampli?er oper ation to a predetermined point on the linear portion of the ampli?er grid potential-plate current characteristic, a recti?er tube coupled to the ampli?er output circuit to rectify audio sig— nails, a resistor connected in the space current path of said recti?er for'developing an ampli?er grid biasing voltagewhich varies in magnitude 60 65 3 2,120,995 with the amplitude of the audio signals im pressed on the recti?er, means for impressing ampli?er tube and having a magnitude such that said varying bias voltage on the ampli?er grid the direct current voltage developed thereacross, by recti?cation of said alternating current, is in a sense to decrease said negative bias, and su?icient to maintain said control grid at a pre the magnitude of said Varying biasing voltage being maintained Within such limits as to operate the ampli?er over the linear portion solely of its said characteristic. determined negative direct current potential with respect to the cathode, a second recti?er 5. In combination with an electric wave am pli?er tube, a source of waves, to be ampli?ed. coupled between the wave input grid and cath ode of said tube, said cathode being at a rela tively ?xed potential, a source of alternating current energy, a recti?er circuit, including an 15 impedance, coupled to said alternating current source, said impedance being connected in se ries between the said grid and cathode of said circuit, including an impedance, arranged to have waves ampli?ed by said ampli?er im pressed thereupon from the ampli?er output cir cuit, said impedance being connected between 1O the control grid and cathode of said ampli?er tube and having a magnitude such that the di rect current voltage developed thereacross, by recti?cation of said ampli?ed waves, biases said control grid in a positive direction with respect 15 to said cathode. , , ABRAHAM VAN DE RIET.